Silicate phosphor is used for a fluorescent, a cathode-ray tube, a luminous body, a vacuum ultraviolet excitation light emitting element and the like. Specifically, for a vacuum ultraviolet excitation light emitting element such as PDP, an improvement of the brightness of the element has been highly desired, and therefore, an improvement of the brightness of the silicate phosphor has been required.
A silicate phosphor is conventionally produced by calcining a mixture of metal compounds, and silicon oxide is used as a metal compound for a source of silicon. One of the examples of the method for producing a silicate phosphor is described in JP No. 09-316444A. According to this method, a silicate phosphor for electron beam excitation represented by a composition formula of Y1.84Tb0.14SiO5 is produced by mixing yttrium oxide, terbium oxide and silicon oxide and calcining the obtained mixture at 1580° C. for 4 hours under reductive atmosphere, wherein the particle diameter of the used silicon oxide calculated from specific surface area is 0.5 μm (5.5 m2/g as converted to specific surface area). However, a production method for a silicate phosphor having higher brightness has been still required.
The object of the present invention is to provide a method for producing a silicate phosphor having high brightness and the silicate phosphor produced by the method.
The present inventors have conducted intensive studies in a method for producing a silicate phosphor by calcining a mixture of metal compounds and directed their attention to the characteristics of silicate raw material as a powder. As a result, the present inventors have found that a silicate phosphor having higher brightness can be produced by using silicon oxide having BET specific surface area of not less than 10 m2/g, which resulted in the completion of the present invention.